Method of and device for pivoting articles



May 16, 1961 c.J.P1ERcE,JR

METHOD oF AND DEVICE FOR PIvoTING ARTICLES Filed Deo. 29. 1959 7 Sheets-Sheet 1 INVENTOR. Chesfer l Pierce, Jr.

l W ATTORNEY May 16, 1961 c. J. PIERCE, JR

METHOD OF AND DEVICE FOR PIVOTING ARTICLES Filed Dec. 29, l1959 7 Sheets-Sheet 2 N .mi

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W ATTORNEY May 16, 1961 c. .1.- PIERCE, JR

METHOD OF AND DEVICE F'OR PIVOTING ARTICLES Filed Dec. 29. 1959 '7 Sheets-Sheet 3 INVENTOR. Cheser f Pierce, fr.

M ATTORNEY May 16, 1961 c.J.P1ERcE,JR

METHOD OF AND DEVICE FOR PIVOTING ARTICLES 7 Sheets-Sheet 4 Filed Dec. 29. 1959 INVENTOR. Cheser J'. Pierce, J5".

A ATTORNEY May A16, 1961 c. J. PIERCE, JR 2,984,332

METHOD OF AND DEVICE FOR PIVOTING ARTICLES Filed Deo. 29. 1959 7 Sheets-Sheet 5 INVENTOR. Cheszer J Pierce, Jr.

ATTORNEY May 16, 1961 c. J. PIERCE, JR

METHOD DE AND DEVICE EDR PvoTING ARTICLES Filed Dec. 29. 1959 7 sheets-sheet s m .Mi v z.. A E o o A L; oooooooooo o, oooo ooooo QM. I o O n@ E @E o OOOOOOOOO OOO OOOOOOO DE VD DE! A. mm, hm. 0 N .WMM o w Y; oo ooo o uw Now D @mw um .Q o.. o NF w ooooooooooooo ooooooo m o NN vv o w ATTORNEY 7 Sheets-Sheet 7 M ATToR/vEy May 16, 1961 c. J. PIERCE, JR

METHOD oF AND DEVICE FORPIVOTING ARTICLES Filed Dec. 29. 1959 \W vw f w WVMW@ JWMMM@ m United States Patent METHOD OF AND DEVICE FR PIV OTING ARTICLES Chester J. Pierce, Jr., Palo Alto, Calif., assignor to Baljak Corporation, Wilmington, Del., a corporation of Dela- Ware Filed Dec. 29, 1959, Ser. No. 862,508

Claims. (Cl. 198-33) This invention relates to improvements in devices for pivoting articles about a vertical iaxis while the articles are being advanced by a conveyor.

The general purpose of pivoting articles is best explained by speciflic examples from which other specilic iuses and applications of the invention will suggest themselves.

It may be assumed that Ithe articles in question are folding boxes, and that it is necessary to turn the boxes in such a way that the leading wall of the box becomes `a lateral wall or that a lateral wall becomes either a leading or a trailing wall.

In the assembling, filling, Iand closing of folding boxes it is often necessary to turn the boxes about a vertical axis by a 90 degree turn. The need for pivoting the boxes may arise from the necessity to apply imprints or labels first to one box wall and then to another, or it may be necessary to turn the box in order to fold or glue rst certain ila-ps or panels by mechanical equipment along the conveyor and then other flaps or panels. In handling frozen food boxes it is generally desirable to have the box cover ina lateral position during filling and it is then preferred to pivot the box 90 degrees before moving the box through a closing and cover locking unit.

One of the most elementary box turning devices is the right-angle conveyor mechanismin which a first conveyor moves the box to its end, where the box cornes to rest, land where the box is then picked up by a second conveyor extending at right angles to the lirst conveyor. As a result of the right angle arrangement a leading w-all of the box becomes a lateral wall on the second conveyor, and an initially lateral wall becomes either a leading or trailing wall. Right angle conveyors occupy a substantial amount of floor space and involve the further disadvantage that it is necessary to bring the box to a stop after moving it in one direction and then accelerating the box in a different direction. 'I'his may entail dislocation or loss of box contents, if the box is filled, but not yet closed.

Another known form of pivoting device comprises a conveyor which moves the `box against a stop or flag extending laterally into the conveyor track, whereby one leading corner' of the box is arrested while the remainder of the box keeps moving land pivots around the `stop or flag. Conversely, it has been proposed to pivot boxes by an element moving up from behind the box and striking the box near one trailing corner as a result of which the box lalso pivots. The last mentioned forms of devices generally require the use of a conveyor which moves the boxes solely by frictional engagement with the box bottom, in distinction from means for positively advancing the box, such as conveyor lugs.

Friction ytype conveyors are disadvantageous for handling boxes made from wax coated stock for the reason that the conveyor tends to pick up a wax coating from the boxes, `as a result of which the friction between the boxes and the conveyor is laltered in an uncontrollable degree. Also, it is practically impossible to maintain `boxes accurately spaced and properly timed. Boxes movreice ing against a flag or stop are not properly turned, if the space between successive boxes is insuliicient, leading to jamming of boxes on the conveyor.

A still other form of conveying and box pivoting devices comprises two substantially parallel belts moving at different speeds, one engaging the box bottom near one lateral wall and the other belt engaging the box bottom adjacent the opposite lateral wall. In mechanisms of this type the degree of frictional engagement is of importance, and the reduction of friction, for example as a result of a coating of wax collecting on the conveyors, makes the mechanism unreliable.

The present invention provides a device for pivoting articles which handles the articles positively, rather than frictionally, so that its operation remains unaffected by frictional characteristics of the boxes. The boxes are pivoted without suddenly stopping or accelerating them 0r ydisturbing their contents, a factor which is of great importance in the handling of frozen food boxes before the closing of the boxes.

The invention permits the boxes to be pivoted at a predetermined rate of pivotal motion. Before, during and after the pivoting of the box, the `box center moves in a substantially straight line, so that the invention may form part of a straight conveyor line. Boxes leave the pivoting device accurately spaced and timed so that no diiiicultes are encountered in subsequent operations, for example in the cover closing and locking operation in which certain elements of the cover closing machine must accurately engage specific portions of the cover structure.

The various objects, features and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, a preferred embodiment of the invention. The linvention also resides in certain new and original features of construction and combination of elements as well as steps and sequences of steps, as hereinafter set forth and claimed. Although the characteristic features of the invention which. are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description, taken in connection with the accompanying drawings forming a part of it, in which:

Figs. fl to 6 are perspective views of successive portions of a box pivoting conveyor mechanism illustrating the construction of the mechanism and the handling of boxes in accurately spaced and timed relationship; `and Fig. 7 is a perspective view, partly in Section, of a structural `detail of the mechanism permitting adjustment of the mechanism to `boxes of different sizes.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to `be. generic in their application. Corresponding reference characters refer to corresponding parts in the several liguresof .the drawings.

The drawings accompanying, and forming part of, this specication disclose certain specific details of construction of the invention for the `purpose of explanation of broader aspects of the invention, 4but it is understood that structural details may `be modified in various respects Without departure from the principles of the invention'and that the invention may be incorporated in other structural forms than shown.

The vbox pivoting device shown in the drawings `constitutes a section of a straight conveyor line moving folding boxes from a filling unit located to the right of the observer, and not visible in the drawings, to a box closing unit on the left, a portion of the box `closing unit 4being visible in Fig. 6.

' evenly spaced from one another.

Filled boxes arrive from the right on a supply conveyor 11 comprising opposite L-shaped rails 12 and 13 on which the boxes are supported. The boxes are positively advanced by a conveyor chain 14 having lugs 15 which engage the trailing end wall of the boxes and ad- Vance the boxes at a predetermined rate of speed and The conveyor chain 14 is trained over a sprocket gear (not visible) on a shaft 16 and the lower run of the chain 14 is visible just below the upper run at 14'.

The boxes B are fed into the device for pivoting them. The illustrated form of device comprises opposite rails 17 and 18 which engage the back and front walls 19 and v 20 of the boxes. In the illustrated orientation the front and back walls are lateral walls and dene the width w of the box. End walls 21` and 22 define the length l of the box, the end wall 21 being the leading wall, and the end wall 22 being the trailing wall of the box which moves in the direction of the arrow 23.

The distance between rails 17 and 18 is slightly greater than the width w allowing a certain degree of play, so that the boxes do not experience an undue amount of friction when moving between 4the rails.

Three boxes, B0, B1 and B2, are shown in Fig. 1. The motion of the box B1 will be described specifically in its various positions. The boxes B and B2 represent preceding and subsequent positions for convenience of cornparison.

The weight of the boxes is supported by three parallel rails 24, 25 and 26 on which the box bottoms rest. Two endless conveyors are employed for pivoting the boxes,

. a major function of one conveyor being to advance the boxes initially and pivot them, a major function of the v other conveyor being to control the pivoting, and to advance the boxes after pivoting. As will be seen, the first conveyor is designed to engage the trailing wall of the boxes, as the boxes are initially oriented and the other conveyor is designed to engage a lateral wall so `as to furnish a pivot point which, however, is not stationary, but moves, so that the steady advance of the boxes is not interrupted.

The endless conveyors may be arranged either underlneath of or alongside the track within which the boxes move, the speciiic location being a matter of engineering preference, or a matter to be decided on the basis of the availability of space. In the illustrated embodiment of the invention the conveyors are laterally arranged with respect to the box track and their feed and return runs lie in substantially the same horizontal plane.

A first conveyor 27 carrying lugs 28 is trained around a terminal sprocket gear 29 which is so arranged that the lugs 28 enter the space of the track immediately behind the trailing wall of the box advanced into the track by the supply conveyor chain 14. The linear velocity of the conveyor 27 is equal to, or slightly greater than, the velocity of the supply conveyor 14.

The illustrated form of machine handles frozen food boxes of a bottom dimension of about 100 by 125 mm. or

. approximately 4 by 5 inches and is capable of turning 400 the conveyor 27 are spaced 300 mm. (or about 12 inches) apart, whereas the lugs 31 of the conveyor 30 are spaced 200 mm. (or about 8 inches) apart, the gearing being such that the conveyor 30 advances 200 mm. in the same period in which the conveyor 27 advances 300 mm., a velocity relationship of two to three. The drive mechanism which accomplishes this will be described later in connection with Figs. and 6. At this point it is suflcient to note that because of the difference in conveyor speeds the lugs 28 catch up with, and yadvance beyond the lugs 31.

In the position in which the box B1 is Shown in Fig. 1 the rails 17 and 18 prevent pivoting of the box even though the box is about to be advanced by an oE-center propelling force exerted by the lug 28 on the trailing Wall immediately adjacent the trailing box corner on the box cover side.

Turning to Fig. 2, it is seen that the rails 17 and 18 flare out so that the box B1 begins to pivot, its left leading corner tending to move into the bowed-out portion of the rail 18. At this point a conveyor lug 31 enters the -track space and engages the lateral wall 20 rearward of the leading corner of the box. This point of engagement 33 becomes a pivot point about which the box continues to pivot as the lug 28 tends to move abreast with, and pass, the slower moving lug 31.

Fig. 3 illustrates the instant in which the lug 28 has almost caught up with the lug 31 and the box has moved into a portion of the track between the rails 17 and 18 having a width D which is slightly greater than the diagonal dimension d of the box.

Fig. 4 shows the instant at which the lugs 28 and 31 are abreast, and the box B1 is in a diagonal position between the rails 17 and 18. It will be noted that the point of engagement 33 had not changed appreciably although the lug 31 has advanced beyond the position which it occupied in Fig. 3. The conveyor chain 30 carrying the lug 311 is trained over the bowed-out portion of the rail 14 so that the extent to which the lug 31 extends into the track space remains substantially unaltered. In a similar manner the conveyor chain 27 is trained over the bowedout portion of the rail 17.

In the position shown in Fig. 5 the lug 28 has moved farther ahead of the lug 31 which also advanced beyond its position in Fig. 4. The box B2 in Fig. 5 occupies approximately the same position which box B1 occupied in Fig. 4. During the final phase the lug 31 increasingly assumes the function of propelling the box into a portion of the track which becomes progressively narrower until the track width is aproxirnately equal to the length l of the box and an added clearance c for the lug 28 which still extends linto the track space, but has only slight frictional engagement with the end wall 22 of the box which now is a lateral wall.

Fig. 6 shows the position in which the lug 28 has slipped beyond the box wall 22 and the lug 31 is also about to withdraw from its propelling engagement with the front wall 20 which now has become the trailing wall of the box.

At this point a conveyor of a closing machine 34 takes over the further advancement of the box. The closing machine conveyor comprises chains 35 and 36 and lugs 37 and 38 which engage the trailing wall of the boxes, in the illustrated instant the box B0. The chains 35 and 36 move at the same speed and propel the` box into engagement with a closing roller 39 which folds the box covers 50 down in a manner known in the art.

Figs. 5 and 6 illustrate the drive mechanism which comprises a drive shaft 40 carrying sprocket gears 41 and 42. Chains 43 and 44 extend over lfurther sprocket gears of which one is visible at 45.. Each further sprocket gear 45 is either integral or combined with a beveled gear train which drives ver-tical shafts 46 and l47. The vertical shaft 46 carries the terminal sprocket 48 of the conveyor 30 and the shaft 47 carries the terminal sprocket 49 of the conveyor chain 27, the respective terminal sprocket gears at the other end being 29 and 32 (see Fig. 1). The sprocket 48 has a smaller diameter (16 teeth) than the sprocket 49 (24 teeth), hence the difference in linear speeds of the conveyors 30 and 27.

Fig. y6 also shows that the conveyor chains 35 and 36 are trained around sprocket gears on the drive shaft 40 whereby the closing machine conveyor 35, 36 istimed with respect to the chains 27 and 30 of the box pivoting unit, or Vice versa.

A timed relationship is also established with the chain 14 of the supply conveyor (see Fig. `1). For this purpose a drive chain 51 extends over a sprocket gear 52 on the shaft 16, the other end of the chain 51 being trained over the sprocket gear 53 on the shaft 40.

During pivoting the boxes advance at a nearly uniform speed. A high operating speed of the order of 400 boxes per minute is permissible, as was established by tests in which dry beans were placed in the open boxes. Dry beans were used for test purposes since their shape and slippery surface makes them sensitive indicators of uneven motion and sudden acceleration and deceleration of the boxes.

The box pivoting mechanism is adapted to handle boxes of different sizes, the length l of the boxes being the principal dimension to which the mechanism must be adjusted.

For the purpose of adjustment the mechanism is split down the center of the box track, so that the two halves of the mechanism may be moved closer together, or farther apart, as may be required.

Fig. 7 illustrates one of several telescoping transverse stud assemblies 54 (see also Fig. 3) which connect the substantially U-shaped longitudinal members 55 and 56 which constitute the bed of the mechanism. Each transverse stud assembly 54 comprises an inner cylindrical element or stud 57 within a hollow sleeve 58.

The stud 57 is welded to the member 55 at 59 and its end is internally screw threaded at 60.

The hollow sleeve 58 is provided with a flange 61 secured to the longitudinal member 56 and encloses a threaded spindle 62` which engages the internal thread 60 of the stud 57. The spindle 62 is provided with shoulders 63 and 64 and carries a sprocket gear 65 on its end 62 which is squared for turning by means of a suitable key or crank. Rotation of the sprocket gear 65 in one direcytion draws the stud 57 into the sleeve 58 to reduce the width of the bed 55, 56 and rotation in the opposite direction increases the width of the bed.

The sleeve 58 is slotted at 67 and the slotted end is provided with lugs of which one is visible at 68. A bolt 69 to which a handle 70 is attached permits the two lugs to be drawn together whereby the slotted end of the sleeve 58 is tightly clamped about the stud 57 after adjustment.

As the drawings show, the transverse shafts, such as shafts 16 and 40 are of suicient length to permit considerable widening of the bed. One of the two bearings of each shaft secures the shaft against axial displacement whereas the other bearing is a plain bushing within which te shaft may slide axially.

Adjustments in the curvature of the rails '17 or 18 are readily accomplished by moving the rails in the desired direction after loosening bolts 71 (Fig. 3) which extend through slotted mounting brackets 72 and 73 on the rails 17 and 18.

As Figs. l to 6 show, there is ample space between successive boxes traveling through the mechanism to accommodate boxes of larger width w than shown. The distance between successive boxes is set by the spacing of the lugs on the conveyors 27 and 30 and need normally not be changed if the mechanism is adjusted to handle boxes of a smaller or larger size.

The illustrated mechanism represents a preferred form of device for the controlled pivoting of boxes and similar articles by rst advancing the box or article at a substantially constant rate of speed by applying a propelling force to the trailing end of the box or article ol center, so as to exert a torque on the box or article about a vertical axis. This torque tends to pivot the box or article, but actual pivoting is initially pervented by application of a stabilizing force to a lateral portion of the box or article. Assuming, for example, that the off center pro- 6 pelling force is applied to the right trailing portion of the box or article, then the stabilizing force is advantageously applied to the left lateral portion of the box or article near its leading end. As a result all portions of the box or article advance substantially in a straight line, without pivoting and at a substantially constant rate of speed.

Then the supporting or stabilizing 4force is: shifted rearwardly by advancing its point of application at a slower rate than the propelled trailing end of the box or article. This leads to pivoting of the box about said point of application.

After the point of application of the propelling force has moved abreast the point of application of the stabilizing force, the propelling force is withdrawn, and thereafter the portion of the box or article opposite the stabilizing force is laterally supported against shifting away from the point of application of the stabilizing force. This causes the box or article to advance at the rate of advance of the stabilizing force.

In the illustrated mechanism the forces are applied by conveyor chains which extend laterally into the path of the box or article. It is evident that the propelling and stabilizing elements may also grasp the box or article from below. Lateral guidance may be provided by stationary elements such as rails, but may evidently also be applied by movable elements. It is therefore apparent that the method may be practiced by other forms of mechanisms than the one shown.

What lis claimed is:

l. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain width, length, and diagonal dimension, the device comprising means forming a track for said articles, said track comprising a first portion of a track width greater than the width of the article but less than said diagonal dimension, a sec ond portion of a track width at least equal to the diagonal dimension, and a third portion having a track width greater than the length of the article, but less than the diagonal dimension; a first conveyor comprising first lugs extending into said track to one side of the track center for advancing articles along the track by engaging the trailing portion of an article, considering the article when moving within the vfirst portion; a second conveyor comprising second lugs extending into the track` to the other side of the track center for engaging a trailing portion of the article moving within the third portion; and means for driving said rst and said second conveyor at a predetermined ratio of linear speed, the speed of the first conveyor being higher than the speed of the second conveyor.

2. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain width, length and diagonal dimension, the device comprising means forming a track Vfor said articles, said track comprising a lirst portion of a track width greater than the width of the article, but less than said diagonal dimension, a second portion of a track width at least equal to said diagonal dimension, and a third portion having a track Width greater than the length of the article, but less than said diagonal dimension; a first conveyor comprising first lugs extending into said iirst track to one side of the track center for advancing articles along the track byengaging the trailing portion of an article, considering the article when moving within the first portion; a second conveyor comprising second lugs extending into the track to the other side of the track center for engaging a trailing portion of the article, considering the article when moving within the third portion, the spacing of the second lugs being less than the spacing of the rst lugs; and means for driving said first and said second conveyor at a predetermined ratio of linear speed, the speed of the first conveyor being higher than the speed of the second conveyor.

`3. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain width, length, and a diagonal dimension, the device comprising a pair 7 of opposite lateral rails adapted to engage and guide side walls of the articles, and forming a track within whichv the articles may move, said track comprising a first portion within which the rails are spaced a distance greater than the width but less than the diagonal, a second portion of gradually increasing spacing of the rails to a maximum not less than the diagonal, whereafter the spacing decreases, and a third portion extending from the second portion, the spacing of the rails within the third portion being greater than the length but less than the diagonal; a first conveyor comprising first article engaging lugs extending into the space between the rails closer to one rail than to the other; a second conveyor comprising second article engaging lugs extending into the space between the rails closer to the other rail than to said one rail, the distance between successive second lugs being less than the distance between successive first lugs; and means for driving said first and said second conveyor at a predetermined ratio of linear speed, the speed of the first conveyor being higher than the speed of the second conveyor.

4. A device for pivoting articles, such as boxes, the device comprising, means forming a track for said articles; a first conveyor comprising first lugs extending into the track to one side of the track center, said first lugs being adapted to engage articles on the track at their trailing portion; a second conveyor slower than said first conveyor, said second conveyor comprising second lugs extending into the track on the other side of the track center, the second conveyor being so timed with respect to the first conveyor that at an uptrack point prior to the pivoting of the article a second lug is in advance of a first lug by less than the length of the article and in a position to engage one wall of the article from one side of the track and that, at a downtrack point after pivoting of the article, the said first lug is in advance of said second lug in a position to engage another wall of the box from the opposite side of the track.

5. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain length, width and diagonal dimension, the device comprising, in combination, a first endless conveyor including first lugs thereon spaced a certain distance from one another; a second conveyor alongside said first conveyor, said second conveyor including second lugs thereon spaced from one another less than said certain distance, the path of the second lugs being spaced from the path of the first lugs less than said diagonal dimension; the second conveyor being so arranged relatively to the first conveyor that the second lugs move into the path of boxes after engagement of the boxes by said first lugs; means for driving said conveyors in timed relationship, said first conveyor being driven faster than said second conveyor, the timing being such that at an initial portion of the article advance a second lug is in advance of a first lug by less than the article length; and that at a final portion, the same second lug is behind said last mentioned first lug by more than said width.

6. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain length, width and diagonal dimension, the device comprising, in

combination, a first endless conveyor including first lugs "path of the second lugs in such a manner that within a first article path portionopposite lugs are spaced less than said width, that within a second path portion downstream from said first portion opposite lugs are spaced moreV than said width, but less than said diagonal dimension, and that within a third path portion downstream from said second portion opposite lugs are spaced less than said length; and means for driving said conveyors at different speeds, the first conveyor being driven faster than said second conveyor, and in a certain timed relationship such that within said first portion a second lug is in advance of a first lug and that within the second portion the last named first lug advances beyond said second lug.

7. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain length, width and diagonal dimension, the device comprising, in combination, a first endless conveyor including first lugs thereon spaced a certain distance from one another; a second conveyor alongside said first conveyor, said second conveyor including second lugs thereon spaced from one another less than said certain distance, each conveyor including a feed run moving in the direction of the articles and a return run moving in the opposite direction, both runs lying in substantially the same horizontal plane; lateral article guiding rails forming a track within which the articles move, the feed runs being trained over said guide rails with their respective lugs extending into the track, the rails being spaced within a first track portion more than said width, but -less than said diagonal, within a second track portion downstream lwith respect to said first portion more than said diagonal and, within a third track portion downstream with respect to the second portion, more than said length, but less than said diagonal; and means for driving said conveyors in timed relationship, the first conveyor being driven at a higher linear rate than the second.

8. A device for pivoting articles, such as boxes, having a substantially rectangular base of a certain width, length, and diagonal dimension, the device comprising means forming a track for said articles, said track comprising a first portion of a track width greater than the Width of the article but less than said diagonal dimension, a second portion of a track width at least equal to the diagonal dimension, and a third portion having a track width greater than the Ilength of the article, but less than the diagonal dimension, said track forming means being split lengthwise of the track to form a right track section and a left track section having freedom of adjustment towards, and away from, the right track section; means for adjustably securing together said two track sections; a first conveyor comprising rst lugs extending iuto said track to one side of the track center for advancing articles along the track by engaging the trailing portion of an article, considering the article when moving within the first portion; a second conveyor comprising second lugs extending into the track to the other side of the track center for engaging a trailing portion of the article moving within the third portion; and means for `driving said first and said second conveyor at a predetermined ratio of linear speed, the speed of the first conveyor being higher than the speed of the second con'- veyor.

9. The method of pivoting a box supported on a box bottom engaging track, the method comprising, the steps of first advancing the box at a substantially constant rate of speed by applying a propelling force to the trailing wall of the box sufficiently close to one of its corners, thereby exerting a torque on the box about a vertical axis tending to pivot the box; simultaneously supporting the lateral wall remote from the point of application of the propelling force sufficiently to advance all portions of the box substantially in a straight line without pivoting; then concentrating the support of the said lateral wall at a point rearward of the leading box corner and advancing this point at a substantially constant linear rate slower than the rate of advance imparted by said propelling force, thereby causing the box to pivot about said point; and removing the propelling force after its point of application has moved abreast of the said point by substantially the length of the rear wall which now is substantially aligned with the direction of the advance of the box.

"10. The method of pivoting a box supported on a box bottom engaging track, the method comprising, the steps of rst advancing the box by engaging the trailing Wall of the box sufficiently close to one of its corners at a rst point and advancing said point in a substantially straight line, substantially normal to the direction of the trailing Wall at a substantially constant first rate of speed; supporting the lateral wall which is remote from said trst point, at a second point rearward of the leading box corner and advancing the second point at a substantially constant rate slower than the rst rate of speed, parallel to the rst point and also in a substantially straight line, thereby causing the box to pivot about the second point; and removing the force applied at said rst point after the first point has moved abreast of the second point by a distance substantially equal to the length of the rear wall which after pivoing is substantially aligned with the direction of advance of the box.

References Cited in the le of this patent UNITED STATES PATENTS 907,116 Baker Dec. 22, 1908 

